This invention relates to an apparatus for separating articles which, advanced serially on a first conveyor with a first conveying speed, are at least in a partial engagement with one another. The articles are transferred onto a second conveyor with a second conveying speed which is greater than the first conveying speed. Because of this speed difference, the articles are advanced on the second conveyor at a greater mutual spacing than on the first conveyor. A third conveyor, provided with article carriers, advances the spaced articles to a packing machine.
It is known that in the packaging art, in order to utilize the full capacity of a machine, the articles to be packaged have to be admitted thereto in a sequence which can be set to the operational cycle of the machine. To be able to fulfil this condition, conventionally a conveyor is provided, by means of which the distance between two successive individual items is changed (increased). For this purpose, a first conveyor is succeeded by a second conveyor which, as noted above, runs with a greater speed than the first conveyor to thus effect an increase of the distance between the articles.
An arrangement of the above-outlined type is described, for example, in German Offenlegungsschrift (published non-examined application) No. 2,346,407. In the machine described therein, the individual items, as they are advanced in a contacting series on a first conveyor belt, are transferred to a second conveyor belt which has a greater conveying speed, as a result of which the individual items have an increased distance from one another on the second conveyor. There is provided a third conveyor which is equipped with article carriers and which serves to adjust the individual items to an exact distance from one another prior to introducing them into a packing machine. A sensor which is provided between the first and the second conveyor belts is intermittently actuated such that the period of it actuated state corresponds to the length of the individual items as they are advanced with the conveying speed on the first conveyor belt. The conveying speed of the first conveyor belt is controlled with the aid of such a length measurement, while taking into consideration the phase position of the third conveyor.
In case the individual items are, for example, chocolate bars having an irregular shape and a length tolerance of .+-.10%, the above-described dynamic control may lead to erroneous distances between articles, resulting in an incomplete utilization of the capacity of the packing machine. Further, such a conventional regulation could work effectively only during operation in the routine run: in case of sudden changes in the output such as an emergency stop or high-acceleration start, the operational safety in a machine operating with a packaging frequency of at least 200 articles per minute could be insufficient.
Swiss Patent No. 619,667 discloses an apparatus in which between the second and third conveyor, that is, between the conveyor belt and the conveyor for introducing the articles into the packaging machine with carrier members, there is provided a stop plate with which cooperates a sensor which, by means of a limit switsch synchronized with the third conveyor, controls the distance between the separated articles and thus controls the second conveyor. It is a disadvantage of such an apparatus that in case of an emergency stop, the articles, because of their inertia, shift in their direction of travel relative to the conveyor belt in an uncontrolled and impermissible manner so that a disturbance-free automatic restart cannot be effected. The stop plate constitues a discontinuity in the conveyor path and reduces the operational safety of the apparatus due to the discontinuous conveyance of the individuals items and the increased friction inherent in its operation. Further, the separation of the articles is effected solely by the third conveyor with which the articles are taken from the stop plate. This circumstance causes a momentary standstill followed by an acceleration of the articles, and thus, the machine output has to be made dependent on the type of the articles. In case of fragile items the approximate maximum permissible output was found to be 200 items per minute.